Fire extinguisher



H. w`. DouGHTY FIRE: EXTINGUBHER Filed April 27, -1927 Carbon +e+racl1londe INVENTOR www? ATTORNEYS aptexited` Jam-'15, v1;929.` I

`UNITED STATES-PATENT OFFICE.

Bowman lwmlums novum, or

AIHEBST, ISSACHU rm nxrnmunsmmy This invention relates to fire extingushers, and particularlyto a self-contained fireextinguishing unit which is adapted to function automaticallywhen the ltemperature in the vicinity thereof rises beyond a predetermined point for the purpose of spraying a fire-extinguishing liquid over surfaces in the vicinity of the extinguisher.

In Letters Patent No. 1,157,090 I have described a fire-extinguishing unit including inner and outer containers, the inner container being adapted to hold a supply of a non-inflammable liquid' havin a relatively low boiling point, such as car on tetrachloride, while the space between the inner container and the wall of the extinguisher contains a solution which when heated is adapted to release gas and to create suiiicient pressure so that the contents of the extinguisher may be ejected.' A concentrated ammonia solution, by which is meant the vconcentrated ammonia water solution of commerce containing, both ammonium hydroxide and ammonia gas'land, which is made by dissolving ammo? nia gas inwater, is a suitable gas-generating agent because when the solution is heated the G ammonia gas becomes insoluble ,and the development of pressure in the extinguisher is, therefore, comparatively rapid.

The common metalspsuch as iron and copper which are fre uently used in manufacturing receptacles or` tire extinguishers, are not affected materially by carbon Ytetrachloride or ammonia in the absence of air but are attacked by ammonia and carbonA tetrachloride together and hence are not available for .extinguishers of the type herein described.

These metals can be protected to a ce1-'tain extent by coating them with metals such as tin,

nickel or silver, which resist the action'of ammonia and carbon tetrachloride. Inevitaf bly, however, the coating is not complete, that y is to say,it contains pin holes or the surface is not covered completely at the joints so that the metal-forming the body of the container is gradually attacked by the corrosive solutions andthe casing is eventually weakened.-

/ While extinguishers may be made from coated metals their life is relatively short and they are not entirely satisfactory because of the" danger of deterioration and possible weakening of the walls to a point which precludes the development of a satisfactory pressure 0`r resilsllts in premature rupture of the extingu er.

. It is the object of the present invention to 1 scribed Application led April 27, 1087. Serial' No. 186,848.

not deteriorate although permitted to stand g for longperiods.

Metals such as tin, nickel and silver, which resist the action of ammonia and carbon tetrachloride, are much too expensive to permit the use thereof as containers for ire extinguishers. .I have discovered, however, thatk A aluminum is not attacked by carbon tetrachloride and ammonia solutions and that it is well suited, therefore, for use in manufacturing containers for re extinguishers of the type described. Furthermore, it is light in weight can be easily shaped by drawing or otherwise and can be finished attractively so that the iire extinguisher may be produced and finlshed by slmple operations and' at a minimum cost. v

In carrying out the inventionfthe outer container alone may be made ofaluminum with an inner container of glass or earthenware, or, if lightness is essential, the inner container maybe made also of aluminum.

the inner 'container because of the low heat conductivity of such materials. Premature vaporization of the carbon tetrachloride in the mner container is thus avoided. The containers are disposed one within the` other so that their kwalls are spaced apart and they are of such relative dimensions as to form a space havin the required capacity for the ammonia so ution. The inner receptacle is intended to receive the fire-extinguishing liquid such as carbon tetrachloride which is ejected under the influence of the pressure de- Y veloped through a tube extending 4from the top of the extlnguisherto a point adjacent the bottom of the cinner receptacle. The outl let from the tube may be closed by a thin diaphragm of metal foil, such as tin 'or aluminum foil, which is adapted to be ruptured when the pressure wit-hin the extinguisher lass or earthen-ware isused preferably for reaches a predeterminedpoint. When the` i diaphragm is ruptured theJ liquid is ejected y, however, the'extinguisheris closedby a cap which lis held in place by a fusible link in themanner well known in fire-extinguishing sprinklersystems. The link is made of ,and preads over the adjacent surface. Preflerab a`metal which fuses whenthe temperature in the vicinity rises abovethe normal temperature to a predetermined extent, thatis to`say, when the atmosphere isheated by the'pres ence of fire in the vicinity. The increased temperature simultaneously causes the ammonia in the solution thereof to be vaporized with a consequent rise in pressure within 'the extinguisher. When the fusible link-is thus fused the pressure already developed within the extinguisher will cause the cap to be lifted from the end'of the discharge tube or nozzle and Will discharge the liquid therefrom upon the adjacent surface.

yAmong the advantages of aluminum as a material for lire extinguishers of the type described in addition to the advantages already `noted is its relatively high heat conductivity. Since the efiiciency of the extinguisher depends primarily upon the rapid heating of the ammonia solution to release ammonia gas therefrom, it is apparent that lthe sensitivenessy of the extinguisher is increased materially by the rapidity with which heat in the atmosphere surrounding the extinguisher will be transmitted through the wall of the extinguisher whenthe latter isy made of aluminum. v

It will be understood that Ithe dimensions and form of the extinguisher may be varied considerably and that the device as illustrated in the accompanying drawing is merely an example of an extinguisher embodying the invention. In the drawing the figure is a vertical section through the extinguisher. I

AReferring to the drawing, 5 indicates a casing of aluminum which may be relatively thin-walled and may be produced, therefore,

by a drawing operation. It is provided with a flange 6 at the top which is adapted, to receive a cover 7 also preferably of drawn aluminum. A gasket 8, preferably of paper coated, for example, with shellac to make a tight joint, is disposed between the cover and the flange 6 and the parts are held in assembled relation by rings 9 and 10 preferably made of a hard metal such as steel, brass, aluminum bronze, duralumin etc., and by screws 11 having nuts 12 thereon. A bail 13 is likewise secured to. the extinguisher Nby the screws 11 at opposite sides thereof which extend through flanges 14 on the bail.

il The innerv receptacle 15 may be of glass or earthen-ware but preferably it is lalso made of drawn aluminum. l It is of suin'cient size 4 to forma space 16 between it and the wall of the shell 5 with ample capacity for the quantity of ammonia-solution whlch is required to effect the discharge of the carbon tetrachloride or other liquid contained in the inner receptacle. Spacers 17 may be disposed in the bottom of the shell tosupport the inner receptacle 15. v

A tube 18 extends through the cap 7 to which it is-secured by nuts 19 and 20 and a gasket 21 preferably of paper coated with shellac. The tube is sufficiently long to reach substantially to the bottom of the inner receptacle I15 and, carries on its outer end a in temperature above the normal point the link will fuse, thus releasing the cap and permitting the discharge of the liquid contents of the extinguisher under the iniuence of the pressure developed by the simultaneous heating of the ammonia solution.,

A tube 26 is secured in the cap 7 by nuts 28 and a gasket 29 and a knurled cap 30 is threadedly supported thereon. This cap is normally in place and prevents the escape of any liquid through the tube. When the extinguisher is filled the cap 30 isv removed to permit 'egress of the air therein contained. The'proper amount of ammonia solution is then introduced to the tube 18.. The carbon tetrachloride in proper proportion to fill the inner receptacle 15 is then introduced through the tube. The ammonia solution, being lighter, will overflow into the space between the shell and the inner receptacle. The cap 30 is then replaced and the cap 23 is placed in position and secured therein by the fusible link. The extinguisher is then in condition for use. It may be hung at a convenietn point by means of the bail 13 and may remain there until such time as it may be required, for fireextinguishing purposes. Should the temperature of the surrounding atmosphere rise at any time by reason of the presence of fire in the vicinity of the extinguisher, the fusible link will melt and the ammonia solution will at the same time release ammonia for the purpose of ejecting the fire-extinguishing liquid from the extinguisher.

Owing to the resistance of aluminum to the corrosive effect of carbon tetrachloride and ammonia solution, the extinguisher may rev main indefinitely in the position assigned to `in the extinguisher do not attack aluminum to any= substantial exteiitand that consequently the extinguisher will-remain in a condition for substantially instantaneous use during long periods without attention. The reason tha'tthe aluminum is not attacked to any substantial extent is probably due to the vfact'that it is very quickly superiicially oxidized and the oxide, being insoluble in water, remains permanently on the surface of the aluminum as a Vclosely adhering film which protects the metal against further action.

While the structure ofA a suitable extinguisher has been described in -more or less detail, it will be understood that various changes may be made therein to adapt it to any particular conditions without departing from the invention or sacriiicing the advantages thereof..

I claim 1. In a ire extinguisher the combination of inner and outer receptacles respectively containing carbon tetrachloride and a solution of ammonia, the outer receptacle being. of aluminum to resist the corrosive action of the liquid contents of the extinguisher, an outlet through which the carbon tetrachloride is ejected by pressure developed when the ammonia solution 'is heated and means for normally closing the outlet.

2. In a re extinguisher the combination of inner and outer receptacles of aluminum respectively containing carbon tetrachloride and a solution of ammonia and to resist the y,corrosive action of those/ liquids, an outlet J.. monil solution isheated and means for normally closing the outlet.

3. In a fire extinguisher the combination of an inner and outer receptacle of aluminum respectively containing carbonl tetrachloride and a solution of ammonia, an outlet throu h which the carbon tetrachloride is ejected y pressure developed in the receptacles when the ammonia solutiondis subjected to heat, means for covering the outlet, and a fusible member for holding the means normall closed aga-inst `said pressure until fused by the .heat at a predetermined temperature.

4. In a tire extinguisher containing carbon tetrachloride `and a solution of ammonia, a receptacle of aluminum to resist the corrosive action of the liquid contents of the exl i In testimony whereof I atlixmy signature.

HOWARD WATERS DOUGHTX. 

